St. Vincent Tower

Speaking of fortifications as a science is only possible if one associates a scientific character to the techniques defensive construction. At the end of the 15th century the typical mediaeval fortification was rendered less effective by the emergence of pyroballistic artillery. Progress was unstoppable, and the castle construction was progressively replaced by the fortress. This transformation took various distinct forms, such as the combination of a mediaeval tower and a bulwark. In Portugal, this transition was led by the Italian School, as indeed was the case in the rest of Europe, and resulted in the construction of the Tower of Belém under Manuel I.Defence of the Tagus Estuary - The building of the bulwarked Tower of Belém followed rational guidelines for the protection of the Tagus Estuary drawn up under João II as part of a greater plan for general reorganisation of the armed forces on land and sea. That plan was continued by Manuel I, who was to provide the human and material resources required by Portugal's global expansion.The initial project consisted of an integrated system that included, as fixed resources, Cascais Fortress (a watchtower and an advanced fortress), the Old Tower on the south bank of the river and, facing this on the north bank, a fortified artillery battery located in the area where the Tower of Belém was to be built later. Equipped with heavy armament, the resulting crossfire from these posts would constitute a formidable obstacle to any ship - be it corsairs or from another belligerent nation - that tried to force its way into the estuary. Due to certain limitations - such as the distances between the individual elements, reduced mobility, insufficient reach and other inconveniences - it was decided to build a 1,000-tonne carrack armed with diverse artillery pieces, which added a mobile artillery base to the fixed defence system.All this was obviously still considered insufficient for total protection, so caravel vessels were also built and equipped with heavy guns that were also capable of firing ricochet shots, a technique hitherto unknown. These ships were constantly ready to intervene whenever necessary. The plan was one of great effectiveness, and for 30 or 40 years there were no complaints from the population, which had previously been the victim of raids by North African and Northern European corsairs. This unprecedented and pioneering plan was later to be applied in the whole Portuguese Empire, particularly in the Orient.New artillery - With the passage of time new, diversified artillery was developed in response to new strategic and tactical problems. A new type of ship was developed in Portugal, the first vessel to be propelled exclusively by sail and designed for battle on the high seas: the galleon. Anchored in the middle of the Tagus, the "Botafogo" acted as a support to the river estuary's defence line. It emerged at the same time the Tower of Belém was built (second decade of the 16th century).One should note that the Tower has a unique configuration. While there is great similarity at the structural level with the Cascais Tower, the profuse and sumptuous decoration of the Belém tower makes it unique. After completion of the building work, the Tower of Belém was equipped with artillery to fulfil its role as an element in the first plan of defence of the Tagus Estuary initiated by João II and continued by Manuel I, the first phase of which included the construction of the bulwarked tower in Cascais, which served as a watchtower, and was continued with the installation of the Old Tower (of Caparica or St. Sebastian) on the south Bank of the river and, possibly, with an open artillery battery on the opposite bank.While it was already planned by his predecessor, it was Manuel I who had the Tower of Belém built on a site close to the aforementioned artillery battery, making it possible to create crossfire with the Old Tower on the opposite bank. The planning for the Tower, and the Cascais fort and Old Tower, took into account the new technical and tactical conditions resulting from the development of pyroballistic artillery. Thus, the gun points are not very high above the water level. They are rectangular in form, making it possible to shift the shooting angle, i.e. point the guns in different directions and allow for direct and ricochet firing. The Tower itself served as a watchtower. The wall is lower and thicker than the older fortification method of mediaeval tradition. There is a certain similarity between the architecture of the bulwark's interior and Portuguese warships. The Tower's lower artillery battery could be equipped with material of the typed used in continental and overseas fortresses in the 16th century.